How to remove auto indentations in LaTeX

Changing a global setting like \setlength{\parindent}{0pt} removes all indentations from your document.

\documentclass{article}
\setlength{\parindent}{0pt}

\begin{document}

TeXShop is a well known free TeX/LaTeX editor for Mac.
You can edit a tex file and output as PDF.
To download and install MacTex is the simplest way to begin it.

If you push "Typeset" button in the nav bar,
pdfTeX will automatically run, compile your tex file, and output a PDF in the same folder as the tex file.

\end{document}